Joe Namath, arguably one of the toughest quarterbacks ever to play in the National Football League, recently had both knees surgically replaced. Sports-related joint injuries like the ones "Broadway Joe" suffered never heal.
A joint is the spot where two bones come together. Bones are really quite soft, so their ends are covered with protective, tough cartilage. You may have seen the "gristle" on chicken bones; that's cartilage.
Once cartilage is broken, it never heals. When the cartilage in a knee joint is damaged, the knee can never be the same.
Physicians may operate to remove loose pieces of broken cartilage and to staple damaged cartilage to the bone to keep it from slipping, but they can't make new cartilage grow.
During his playing career, Joe Namath underwent six knee operations. Each time he had surgery, the doctors took out a little more cartilage. But as long as he had some cartilage left to protect the ends of the bones in his knee joints, his knees only hurt when he used them.
Yet, once all the cartilage was gone and bone began rubbing on bone, his knees hurt all the time. That's when his doctors recommended knee replacements.
You don't want to go through all that! When your knees hurt, stop exercising. If your knees continue to hurt, see your doctor. If you try to play with damaged knees, as Joe Namath did, you may eventually need knee replacement surgery.
Q: Should I take salt tablets when I exercise and sweat a lot on very hot days?
A: Fifty years ago, doctors prescribed salt tablets for people who exercised or worked outdoors on hot days. But not anymore.
You should not take salt tablets. Too much salt can thicken your blood, as well as increase your chances of developing clots that can block the flow of blood through your body. Salt tablets can also upset your stomach and ruin your interest in exercise.
It's true you can lose a lot of salt when you exercise in the heat. And if you don't replace that salt, your muscles will hurt and cramp.
However, Americans rarely suffer from salt deficiency, usually taking in much more salt than is needed.
When you exercise for an extended period of time even on the hottest days, your requirement for salt rarely exceeds 3,000 milligrams. The average American takes in between 6,000 and 15,000 milligrams of salt each day, more than twice as much as he or she needs.
But if you become weak and tired from exercising in hot weather, check with your doctor to see if you do, in fact, lack salt. If so, your doctor will probably recommend that you begin adding a little salt to your food.
Dr. Mirkin is a practicing physician in Silver Spring, specializing in sports medicine and nutrition.